class Todo(object):
    current_to_id=1
    @classmethod
    def next_id(cls):
        todo_id=Todo.current_to_id
        Todo.current_to_id+=1
        return todo_id
    def __init__(self,title:str,id:int=0,completed=False):
        self.id=id if id>0 else Todo.next_id()
        self.title=title
        self.completed=completed
